Treatment of oil for removing iron



March 1, 1955 G. F ASSELIN 2,703,306

TREATMENT OF OIL FOR REMOVING IRON Filed May 1, 1952 TREATING REAGENT TOCRACKING OPERATIONS INCORPORA TOR ELECTRICA L PREC/PI TA TOR WATERINVENTOR. George E Asse/in, BY

United States Patent 2,703,306 TREATMENT OF OIL FOR REMOVING IRON GeorgeF. Asselin, Baytown, Tex., assignor, by mesne assignments, to EssoResearch and Engineering Company, a corporation of Delaware moving 1mmfrom mineral oil containing same. More particularly, the invention isdirected to a method for removing iron as salts from mineral oilcontaining same.

In its more specific aspects, the invention is directed to a method oftreating hydrocarbon fractions such as gas oil fractions to make themsuitable for use as cracking stocks.

The present invention may. be described briefly as a method for removingiron from mineral oil containing same which comprises contacting the oilwith an aqueous solution of a reagent selected from the'group consistingof ammonium oxalate and ammonium thiocyanate under conditions of contactand temperature such that the ammonium compounds remove a substantialamount of the iron from the mineral oil to allow recovery of a mineraloil having a reduced content of iron.

In the practice of the present invention the mineral oil fraction iscontacted with a reagent selected from the group consisting of ammoniumoxalate and ammonium thiocyanate. The ammonium oxalate and the ammoniumthiocyanate is employed in an amount in the range from 0.05% to 2.0% byweight in an aqueous solution. The aqueous solution containing thestated amounts of the reagent is employed in an amount in the range fromabout to about 30% by volume of the mineral oil to be contacted ortreated.

The contacting time employed in the practice of the present inventiongenerally should be sufiicient to obtain an intimate mixture to allowthe reagent to come into contact and react with the iron which it isbelieved exists as complex salts in the mineral oil. Specifically acontact time from about 1 second to 5 minutes should be sufficient,although longer times may be employed.

The contacting operation may be conducted in suitable contactingequipment well known to the art; for example, baffie plateincorporators, jet mixers, centrifugal pumps, stirring devices and thelike may be used to obtain the intimate contact.

The contacting operation should suitably be conducted at a temperaturein the range from about 150 to about 300 F. If temperatures below 150 F.were employed, the fraction undergoing treatment might become tooviscous for intimate admixture. If temperatures above 300 F. wereemployed the solubility of the aqueous solution in the fraction beingtreated might be sufiicient to allow the oil being treated to take uplarge quantities of the treating solution. A preferred temperature rangeis from about 180 to about 200 F.

The feed stock employed in the practice of the present inventionsuitably is a gas oil fraction boiling in the range from about 400 toabout 850 F. Such fractions in the processing operations, in travelingthrough a refinery, pick up considerable amounts of iron and also maycontain a considerable amount of iron as salts which may have beenpresent originally in the crude petroleum from which the gas oil isproduced. As a general rule, I prefer to treat heavy fractions sincethese fractions have been contacted with iron surfaces longer than thelighter fractions and moreover the heavy fractions will have the ironsalts concentrated therein. I also may treat, in accordance with myinvention, crude petroleum as it is received-from the well or in thepetroleum refinery. Such crude petroleum fractions are known to'containiron, vanadium and nickel at least partially in a very tightly boundstate, such as porphyrins and similar compounds. It is, therefore,contemplated that the present invention will be also applicable totreatment of crude petroleum. 'In such instances, my

invention may be satisfactorily employed in conjunction with crudepetroleum desalting operations which are well known to the art.

The invention will be further illustrated by reference to the drawing inwhich the single figure is a flow sheet of 3, a preferred mode.

Referring now to the drawing, a gas oil fraction is introduced into thesystem by line 11 from a source, not shown. As the gas oil flows throughline 11 there is added to it by line 12 a suflicient quantity of anaqueous solution of a treating reagent selected from the groupconsisting of ammonium oxalate and ammonium thiocyanate. The gas oil towhich the aqueous solution has been added flows into an incorporator orother mixing device 13. For purposes of illustration a baffle plate typeincorporator is shown. In incorporator 13 an intimate admixture betweenthe treating reagent and the gas oil is effected to allow contactbetween the treating reagent and the iron and other salts contained inthe gas oil. As a result of the admixture or contact there is formed anemulsion of gas oil and treating reagent which is withdrawn fromincorporator 13 by line 14 and discharged into a separa tion means 15illustrated in this particular instance by an electrical precipitator ofa type well known to the art for effecting separation of oil-wateremulsions into their component parts. Although the separation means ofmy inas settlers, centrifuges and the like.

vention is illustrated by an electrical precipitator, it is to beemphasized that this is for illustration purposes only and not by way oflimitation since I contemplate employing as a separation means otherseparating devices such In any event, in separator 15 the emulsion isresolved into its component parts and the aqueous solution of thetreating reagent is withdrawn from the electrical precipitator 15 byline 16 for further use or discard as may be desired while there iswithdrawn from the top of precipitator 15 by line 17 the contacted ortreated oil whose iron content has been substantially reduced by thetreating operation. The treated oil may satisfactorily be used as a feedstock for a catalytic cracking operation of the fiuid type, and thelike.

' The invention will be further illustrated by the following runs inwhich a gas oil fraction containing iron was treated with water in twoinstances and with an aqueous solution containing 0.4% ammoniumthiocyanate. In all instances, the water and the aqueous solution wereseparated from the treated or contacted oil and the oil then tested foriron content and compared. These data are presented in Table I:

It will be noted from the data presented in Table I that treating theoil with water alone resulted in 33% to 39% removal of iron whereas theaddition of ammonium thiocyanate to the water caused the removal of 59%to 64% of iron, nearly a two-fold increase.

Other runs were then made in which 10% by volume of water was employedto wash a gas oil fraction in comparison to runs where the water hadadded to it varying quantities of ammonium thiocyanate. These operationswere conducted at a temperature of 210 to 240 F. As a result of treatingthe oil with water and the water to which ammonium thiocyanate had beenadded, emulsions were formed which were resolved in an electricalprecipitator; the treated oil was then tested for ash content and alsofor iron and sodium. These data are presented in Table II.

. It will be seen from the data in Table II that treating the oil onlywith water resulted in removal of 21% and 73%, respectively, of the ironand sodium while when 0.06% by weight of ammonium thiocyanate waspresent the amount of iron removed was 27%. When 0.09% by weight ofammonium thiocyanate was present in the water, 59% of the iron wasremoved. These data indicate that at least 0.05% by weight of thetreating reagent should be employed in the treating solution.

Another run was made in which an aqueous solution containing 0.4% ofammonium thiocyanate was used to contact a gas oil fraction. In thisparticular instance the ash content originally was 4.4 lbs/1000 bbls.Treatment with 15 volume per cent of the aqueous solution containingammonium thiocyanate at 200 F. effected removal of a sufficient amountof ash to reduce the ash content of the treated oil'to 1.0 lb./ 1000bbls. with 78% ash removal. The treatment effected removal of 64% of theiron. In addition to removing iron, the treatment also substantiallylowered the content of vanadium, nickel, silicon, sodium, calcium,magnesium, ammonium and chromium present originally in the oilundergoing treatment.

Additional runs were made in which a treating solution containingammonium oxalate in one instance and a treating solution containingammonium thiocyanate in another instance was employed to treat a gas oilfraction which was being charged to a catalytic cracking unit. Theseruns were conducted under conditions to form an emulsion which wasresolved in an electrical precipitator and the treated oil was recoveredfrom the electrical precipitator and tested for ash content and thespecific 4 stantial amounts of iron and other metals from hydrocarbonfractions containing same.

The nature and objects of' the present invention having been completelydescribed and illustrated, what I wish to claim as new and useful and tosecure by Letters Patent 1. A method for removing iron from a mineraloil containing same which comprises contacting said oil with an aqueoussolution of ammonium thiocyanate, and recovering said contacted mineraloil having a reduced content of iron.

2. A method for removing iron from a hydrocarbon fraction boiling in therange from 400 to 850 F. containing iron which comprises contacting saidfraction with an aqueous solution of ammonium thiocyanate, separatingsaid aqueous solution from the contacted fraction, and recovering saidcontacted fraction having a reduced content of iron. I

3. A method for removing iron from a hydrocarbon fraction boiling in therange from 400 to 850 F. containing iron which comprises contacting saidfraction with an aqueous solution containing an amount in the range from0.05% to 2.0% by weight of ammonium thiocyanate at a temperature in therange between 150 and 300 F., separating said aqueous solution from thecontacted fraction, and recovering said contacted fraction having areduced content of iron.

4. A method for removing iron from a gas oil fraction containing ironwhich comprises intimately admixing said gas oil fraction with anaqueous solution containing an amount in the range from 0.05 to 2.0% byweight of ammonium thiocyanate at a temperature in the range from 150 to300 F., separating the aqueous solution from the gas oil fraction, andrecovering a gas oil fraction having a reduced iron content.

5. A method for removing iron from a gas oil fraction containing ironwhich comprises intimately admixing said gas oil fraction with an amountin the range from about 5% to 30% by volume of aqueous solutioncontaining an amount in the range from 0.05% to 2.0% by weight ofammonium thiocyanate at a temperature in the range from 180 to 200 F.,separating the aqueous solution from the gas oil fraction, andrecovering a gas oil fraction having a reduced iron content.

content of the various metals and iron as iron oxide. The results ofthese runs are presented in Table III.

Table III Feed Stock Mixing Time, Hours 1.0.

Mixing Temperature, F.

Electrical Precip- Resolution Method itator. Resolution Time, Hours....1.5. Resolution Temperature, 1 184 Arninoniurn Oxa- 0.46 Wt. Percent...

0.46 Wt. Percent...

Chemical Reagent Used "I Concentration of Reagent in Inlet lbs/1,000

MIDI: PPPPPPPPEP oooccoi-wss-ucmaqcnozctaomm Ammonium Thiecyanate.

0.49 Wt. Percent.

0.51 Wt. Percent.

"It will be apparent from the foregoing runs that I have devised aprocess which allows the removal of sub- References Cited in the file ofthis patent UNITED STATES PATENTS 2,411,958 Dietrich et al Dec. 3, 1946FOREIGN PATENTS 518,593 France Jan. 6, 1921

1. A METHOD FOR REMOVING IRON FROM A MINERAL OIL CONTAINING SAME WHICHCOMPRISES CONTACTING SAID OIL WITH AN AQUEOUS SOLUTION OF AMMONIUMTHIOCYANATE, AND RECOVERING SAID CONTACTED MINERAL OIL HAVING A REDUCEDCONTENT OF IRON.